As compressors for air conditioners installed in vehicles, hybrid vehicles, or the like, various types of integrated-inverter electric compressor configured by integrating an inverter unit have been proposed. In the integrated-inverter electric compressor, generally, an inverter accommodating unit (inverter box) is provided at the periphery of a housing accommodating an electric motor and a compressor, and an inverter unit that converts DC power supplied from a high-voltage power supply into three-phase AC power and supplies the three-phase AC power to the electric motor via glass-sealed terminals is integrated inside the inverter accommodating unit.
As described in Patent Documents 1 and 2, in the inverter unit, a power-system board (including a pedestal or unit base) having mounted thereon a plurality of power semiconductor switching elements (IGBTs or the like) that convert DC power into three-phase AC power and a CPU board (printed board) having mounted thereon a control and communication circuit including components that operate at a low voltage, such as a CPU, are provided in two upper and lower layers, and these boards are accommodated inside an inverter case or an external case so that the inverter unit is integrated with the periphery of a compressor housing.
An integrated-inverter electric compressor used in an automobile air conditioner is used under severe temperature and vibration conditions, so that its inverter unit is required to have high anti-vibration properties, anti-humidity properties, and insulation properties. Therefore, Patent Documents 1 and 2 propose an arrangement in which a gel-like resin, such as a silicone gel, is filled inside an inverter accommodating unit in which an inverter unit is integrated, an arrangement in which a CPU board is disposed suspended in a gel-like resin, and so forth. Furthermore, Patent Document 3 proposes an arrangement in which a metallic board, a control board, and an interface board are provided in three layers inside a plastic case, the power-semiconductor surface of the metallic board is filled with a gel material, and the region from the surface to the top face of the control board is encapsulated in resin.